The best-known technology to transform heat to power through mechanical work rests on Rankine cycle. Three different Rankine Cycle are used for heat recovery applications: Steam Rankine Cycle, Organic Rankine Cycle (ORC) and Kalina Cycle which is almost similar to ORC.
Steam Rankine Cycle systems are the best solution to recover heat from very hot temperature source (<350°C) when a large amount of thermal power is available. A well-known application of Steam Rankine Cycle is Combined Cycle Power Plant (CCPP). This type of power plant uses both gas and steam turbine together. The Steam turbine recover waste heat from the gas turbine. However, this system requires steam to be preheated in order to avoid steam condensation which would provoke blades erosion. So Steam Rankine Cycle is not relevant to transform heat into power is the hot source temperature is under 350°C.
Organic Rankine Cycle uses an organic working fluid instead of steam and then applies to heat into power projects where hot source temperature is between 85°C and 500°C.
Kalina Cycle is a variation of the Rankine Cycle. A mixture of water and ammoniac is used instead of steam or organic working fluid.